diff --git a/char32.c b/char32.c
index 4673779..71d2ae5 100644
--- a/char32.c
+++ b/char32.c
@@ -5,6 +5,7 @@
 #include <assert.h>
 
 #include <wchar.h>
+#include <stdc-predef.h>
 
 #define LOG_MODULE "char32"
 #define LOG_ENABLE_DBG 0